An image forming apparatus includes a photoconductor drum for carrying a toner image and a transfer roller placed facing the photoconductor drum for transferring the toner image to a sheet. The transfer roller is pressed against the photoconductor drum and a transfer bias for transferring the toner image to a sheet is applied to the transfer roller. The toner image carried on the photoconductor drum is transferred to the sheet when the sheet passes through the nip between the photoconductor drum and the transfer roller.